1. Technical Field of the Invention
The present invention relates generally to a piston for an internal combustion engine, and more particularly to a piston having improved mechanical strength.
2. Background of the Prior Art
As currently available high-powered internal combustion engines for automotive vehicles are developed, the thermal loads exerted on their engine pistons tend to increase. A piston has been accordingly proposed wherein a piston is internally chilled by the inclusion of a ceramic piston head plate during casting of the piston body to improve the heat resistance of the head plate of the piston which faces a combustion chamber of the engine.
However, there is a problem in that the internally chilled surface of the ceramic piston head is separate from the piston body, causing the ceramic piston head to play and to break due to shocks such as piston slap, since the ceramic piston head and the aluminum piston body do not bond well and the difference in thermal expansion therebetween is great. Additionally, the great difference in thermal expansion of the two materials tends to cause residual stress to be exerted on the piston body during cooling after casting. This results in cracking of the piston body.